W0.2+0.02t is a mathematical expression, where w is a constant of 0.2 and t is a variable, representing a time value. This expression can be used to calculate a value that changes with time. The calculation method is to substitute the time t into the expression and calculate the corresponding value.
W0.2+0.02t means that when the time is t, the size of a certain value is 0.2 plus 0.02t..